I've not done much maxspeed tagging to date, for various reasons, but the main
one is that Map Features says that maxspeed should be in km/h. Or more
accurately looking at the history for the template for that section [1], the
original conversion stated:
"{{{maxspeed:desc|Maximum speed, country-specific units}}"
And the revision 3 minutes later changed it to
"{{{maxspeed:desc|Maximum speed in km/h}}}"
With a description for the edit (from Pieren) of
"(restore metrics text, although it should be discussed)". I don’t know where
to find the versions pre 2008 to find out what it said on older versions.
I noticed that “should be discussed” note, but don’t know where to look for
that discussion. However, the decision to put in km/h has made a mess of the
maxspeed tagging on UK roads, especially as there is both a conversion table in
the wiki quoting whole numbers, and a multiplication factor to use. See for
example Tagwatch [2] where the most common maxspeed is 48, followed by 30mph
(the format I’ve been using), and lower down come 48.28, 48.28032, 48.27808 and
48.3. I’d also guess that the ways tagged as maxspeed=30 mean 30mph. If we had
stayed with assumed country-specific units then the tagging would have been
more consistent, easier for the user to tag, and not require a conversion to a
random number of decimal places.
The maplint mention in the message subject is because Map Features defines the
value for the maxspeed key as being a number, so any way I’ve tagged as =30mph,
20mph, 10mph, national or 40mph (as I did for the first time yesterday) gets
highlighted in the maplint information, rendering it (no pun intended) next to
useless for checking other mistakes I may have made in the tagging.
I have no suggestion what to do about either of these situations though. I
wouldn’t have been bothered at all if maplint hadn’t suddenly started
highlighting lots of ways in the area… I realise that that is down to the word
number in the wiki page causing the validation to fail with the mph in the
value.
Thinking about it I have a similar issue with maxheight. Most of the signs
these days I think quote in metres, but I tagged one the other day as so many
feet and inches (possibly 13’9” – I forget), as I tag what is on the sign and
not what a metric conversion is (to the centimetre, metre, decimetre,
millimetre?). It seems I’m not the only one [3].
I suspect what I’d like most would be for maplint to recognise that if the
value contains valid units for whatever the key is (optional units), then it
wouldn’t highlight the way as in need of checking. I believe maplint is common
to both Mapnik and Osmarender (as it’s highlighting ways on Mapnik which don’t
yet show as I only added them yesterday), and I know how to rebuild the
not-in-map_features information as I did it recently to add some keys that
*were* in Map Features but not being recognised by the [EMAIL PROTECTED] client
when it generated the maplint tiles, but it would probably need the perl code
that creates the XML tweaking to cope with optional units in some way (a bit
like it currently doesn’t like * in the value column, IIRC, or “User Defined”).
It’s raining here incidentally, which is why I thought I’d rant on email
instead of going out mapping a bit more of the area.
Ed
[1]
http://wiki.openstreetmap.org/index.php?title=Template%3AMap_Features%3Arestrictions
<http://wiki.openstreetmap.org/index.php?title=Template%3AMap_Features%3Arestrictions&diff=73032&oldid=73031>
&diff=73032&oldid=73031
[2] http://tagwatch.stoecker.eu/Great_britain/En/keystats_maxspeed.html
[3] http://tagwatch.stoecker.eu/Great_britain/En/keystats_maxheight.html
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